Automatic cutoff mechanism for gas burner



July 2, 1957 HUG AUTOMATIC CUTOFF MECHANISM FOR GAS BURNER Filed Aug.21, 1953 2 Sheets-Sheet l INVENTOR. 644 NS 4 14/ u 6 July 2, 1957 H. A.HUG 2,797,699

. AUTOMATIC CUTOFF MECHANISM FOR GAS BURNER Filed Aug. 21. 195} 2Shets-Sheet 2 i INVENTOR. I

I BY

Arra

atent 2,797,699 Patented July 2, 1957 fiice AUTOMATIC CUTOFF MECHANISMFOR GAS BURNER Hans A. Hug, Boston, Mass.

Application August 21, 1953, Serial No. 375,793

3 Claims. (Cl. 13765) This invention relates to automatic cut offdevices for gas burners and more particularly to an automatic cut oilfor a cookstove burner for cutting off the fiow of gas to the burner inthe event the burner flame is accidentally extinguished with the burnervalve open.

It is among the objects of the invention to provide an improvedautomatic cut off mechanism for a gas burner, such as a cookstoveburner, which will cut off the flow of gas to the burner if the burnerflame is accidentally extinguished while the gas control valve is open;which cuts oif the gas to the burner by reclosing the gas control valve;which does not interfere with the manual adjustment of the gas controlvalve to provide the desired height of burner flame; which automaticallyresets itself for manual adjustment of the control valve at the time itcloses the control valve; and which is simple and durable inconstruction, economical to manufacture and install, and positive andreliable in operation.

Other objects and advantages will become apparent from a considerationof the following description and the appended claims in conjunction withthe accompanying drawings, wherein:

Figure l is a side elevational view of a gas burner and associatedcontrol valve with an automatic cut off mechanism illustrative of theinvention connected between the burner and the control valve;

Figure 2 is a transverse cross sectional view on an enlarged scale onthe line 22 of Figure 1;

Figure 3 is a longitudinal cross sectional view on the line 33 of Figure2;

Figure 4 is a transverse cross sectional view on the line 44 of Figure3;

Figure 5 is a perspective cross sectional view of the gas valve andautomatic shut olf mechanism therefor;

Figure 6 is a side elevational view of a somewhat modified form of gasvalve, burner and automatic cut 011 assembly; and

Figure 7 is a fragmentary top plan view of the modified form of theinvention shown in Figure 6.

With continued reference to the drawings, a gas conduit 10 is connectedto one side of the body 11 of a gas control valve, generally indicatedat 12, by a union 13 of known construction, and a conduit 14 isconnected by a similar union 15 to the other side of the valve body 11.A burner jet 16 extends from the conduit 14 into the open end of thesleeve 17 of a gas burner, generally indicated at 18, having at theother end of the sleeve a hollow ring 19 provided in its upper surfacewith perforations 20 through which the gas flows to feed the burnerflame.

The valve body 11 is provided with a bore 21 extending through the bodyfrom the union 13 to the union 15 and with a tapered opening 22intersecting the bore 21. A tapered valve plug 24 of circular crosssectional shape is disposed in the tapered opening 22 and is providedwith a transverse or diametrical passage 25, which, when in registrywith the adjacent ends of the bore 21, provides a continuation of thebore 21 through the valve body to connect the gas line 10 to the conduit14. When the plug 24 is rotated to a position at which the passage 25 isout of registry with the bore 21, the passage 25 is interrupted and thegas is cut oil from the conduit 14, this being the closed position ofthe valve. The plug may also be turned to various selected positions ofpartial registry of the ends of the passage 25 with the correspondingends of the bore 21 to provide restrictions of different degrees throughthe valve to control the quantity of gas flowing through the valve tothe burner 18 and consequently, the height of the burner flame.

A stem 26 extends coaxially from the larger end of the plug 24 and astem 27 extends coaxially from the smaller end of the plug. A handknob28 is centrally mounted on the stem 26 to provide means for manuallyrotating the valve plug 24 to'selected positions of adjustment relativeto the'valve body 11, and an annular enlargement 29 is provided on theouter end of the stem 27 of the valve plug. A washer 30 having acentrally disposed aperture therein is secured on the outer end of theenlargement 29 and provides a spring abutment, and a compression spring31 surrounds the stem 27 between the washer 30 and the adjacent side ofthe valve housing 11 to apply to the valve plug 24 a resilient forceseating the valve plug in the tapered opening 22.

With the above described arrangement, the valve 12 can be manuallyopened and the gas ignited at the top of the burner ring 19 to providethe burner flame. The

valve can also be adjusted by turning the handknob 28 to regulate theheight of the burner flame and, if desired, the burner may beautomatically ignited by a pilot flame extending from a pilot tube 33having one end disposed adjacent the burner ring 19 and its other endconnected to a centrally located pilot flame housing, not illustrated.The burner ring has an aperture in the side thereof for directing gasinto the adjacent end of the pilot tube when the corresponding burnervalve is turned on, and the flashback of this gas ignites the burner.

Under these conditions, the burner will operate satisfactorily as longas the burner flame is not extinguished. However, if the burner flameshould be extinguished in some manner, such as by a sudden draft, or bythe boil ing over of liquid from a cooking utensil disposed above theburner, gas would continue to flow from the burner as long as the valve12 was left open and could produce a sutficient concentration of gas inthe surrounding air to create an explosion when ignited by the pilotflame or by another burner, the flame of which has not beenextinguished. Even if an explosion were not occasioned, the escape ofgas is always hazardous and unpleasant,

' and is to be prevented insofar as possible.

The present invention provides mechanism for automatically cutting offthe flow of gas to the burner in the event the burner flame isextinguished while the burner control valve is open, and includes anextension 35 on the valve body 11 surrounding the washer 30 and havingat its outer end an annular external flange 36 pro vided in its faceremote from the valve body with a peripheral groove 37. A hollow housing38 has a cylindrical wall 39 received at one end in the annular groove37 and closed at its other end by an end wall 40. This housing isreleasably secured to the valve body 11 by the spring clips 41 angularlyspaced apart around the cylindrical wall 39 of the housing at the openend thereof and engaging the side of the annular flange 36 remote fromthe housing, as illustrated in Figure 2.

A shaft 42 extends at one end through the central aperture in the washer30, and is secured to the annular enlargement 29 on the stem 27 of thevalve plug 24, and this shaft 42 extends into the housing 38. A spiralspring 43 surrounds the shaft 42 adjacent the washer 30 and is securedat its inner end to the shaft 42 and at its outer end to the extension35 of the valve body 11. This spring 43 resiliently urges the shaft 42to turn and to turn the valve plug 24 in a direction to close the valve12. An annular clutch member 44 has a coaxial bore145 through which theshaft 42 extends and this clutch member has at one end an annular flange46 which surrounds the spiral spring 43 and is disposed in opposition tothe adjacent annular surface of the extension 35 of the valve body 11. Aring 47 of friction material is secured to the flange 46 overlying thesurface of this flange opposed to the adjacent surface of the valve bodyextension 35 and a compression spring 48 surrounds the shaft 42 betweenthe end of the member 44 remote from the .flange 46 and a cam disc 49secured on the shaft 42 at the end of the shaft remote from the valveplug 24 to press the ring 47 of friction material against the adjacentsurface of the valve body extension 35 and provide a frictionalresistance to turning of the clutch element 44 and the shaft 42. Withthis arrangement, when the valve plug 24 is turned by the handknob 28 ina valve opening direction, the spring 43 is wound or stressed and biasesthe valve plug in the opposite rotational direction back to its valveclosing position. Movement of the valve plug by the spring 43 is,however, prevented by the frictional engagement of the friction ring 47with the adjacent end surface of the valve body extension 35. Thefriction ring 47 is fixedly secured to the flange 46 of the annularmember 44 and the annular member 44 is connected to the shaft 42 forlimited sliding movement relative to the shaft and against rotationalmovement relative to the shaft by suitable means, such as the key 50disposed in keyways extending longitudinally of the shaft 42 and annularmember 44, as illustrated in Figure 3.

Mechanism responsive to the heat of the flame of the burner 19 isconnected to the clutch element 44 and comprises a tubular coil 52disposed between the burner ring 19 and the adjacent end of the pilottube 33 and connected through a tube 53 to the outer end of a bore 54 ina plug 55 mounted in one end of a sleeve 56 secured at its other end onthe end wall 40 of the housing 38. The bore 54 extends through the plug55 and a tubular extension 59 of reduced diameter extends from the innerend of the plug 55 with its bore in longitudinal alignment with the bore54 of the plug. The extension or sleeve 59 constitutes a guide for aplunger 60 slidably mounted in this sleeve and provided with a pistonformation 61 at a location spaced from the outer end of the extension59.. A longitudinally expansible sleeve 62 of suitable resilientmaterial, such as bronze or brass circumferentially corrugated, issecured at one end to the periphery of the piston formation 61 and atits other end to the peripherey of the plug 55.

The tubular ring 52 and the tube 53 are filled with a suitable heatexpansible material, such as alcohol, and,-

when the flame of the burner 18 is ignited, the ring 52 is heated,expanding the material therein and forcing the plunger 60 and pistonformation 61 in a direction away from the plug 55 and toward the endwall 40 of the housing 38.

If the burner flame is extinguished, the longitudinally expansiblesleeve 62 contracts with the assistance of a spring 63 connected betweenthe plug 55 and the plunger 68 to produce a force somewhat greater thanthe force of the spring 48, pulling the plunger 60 and piston formation61 in a direction toward the plug 55 and away from the end wall 40 ofthe housing 38, for a purpose which will presently appear.

A bifurcated lever 64 has spaced apart and substantially parallel legs65 and 66 disposed at respective opposite sides of the diametricallyreduced end portion 67 of the annular member 44 adjacent the spring 48and pivotally connected to this diametrically reduced end portion of theannular clutch member by suitable means, such as the pivot pins 68 and69. Theselever legs 65 and 66 are spaced apart at one end of the leverand are pivotally connected at this end of the lever to the outer endsof brackets 70 and 71 securedto and extending outwardly from the outerend surface of the extension 35 of the valve body 11. The lever 64 andthe brackets 70 and 71 are all disposed within the cylindrical side wall39 of the housing 38 and, at the end of the lever remote from thebrackets 70 and 71, the lever legs 65 and 66 are brought together andare extended from this end of the lever toward the end wall 40 of thehousing 38, and provided with a detent formation 72 disposed adjacentthe inner surface of the cylindrical side wall 39 of the housing 38.

A toggle spring 73 is connected between the outer end of the bracket 70and a pin 74 projecting outwardly from the outer side of the lever leg65 between the pivot pin 68 and the closed end of the lever, and asimilar toggle spring 75 is connected at one end to the outer end of thebracket '71 andat its other end to a pin 76 projecting from the outerside of the lever leg 66 between the pivot pin 69 and the closed end ofthe lever.

An arm 78 is pivotally connected at one end to the end of the plunger 60remote from the plug 55 and extends through an aperture 79 in the endwall 40 of the housing 38 and past the periphery of the cam disc 49. Atorsion spring 80 connected between the arm 78 and the plunger 60 at thepivotal connection 81 between the arm and the plunger holds the armfirmly against the peripheral surface of the cam disc 49, and a dog 82is provided on the side of the arm 78 adjacent the detent 72 at the sideof the cam disc 49 remote from the housing end wall 40.

When the heat responsive ring 52 is heated up and the plunger 60 forcedaway from the plug 55, as explained above, the arm 78 is moved inwardlyof the housing 38 until the dog 82 is positioned at the side of thedetent 72 remote from the cam disc 49. At this time, a peripheral cam 84on the cam disc will have moved away from the arm 78 by manual openingof the valve 12, so that the dog 82 will engage the detent 72.

Under these conditions, if the burner flame is extinguished while thevalve 12 is still open, the pressure exerted by the heat expansiblematerial in the ring 52 and tube 53 on the piston 61 will be releasedand the longitudinally expansible sleeve 62 and spring 63 will contract,pulling the arm 78 outwardly of the housing 38. The dog 82 on the arm 78engaging the detent 72 on the lever 64 at this time swings the leverabout its pivotal connection with the brackets 70 and 71 until the pins74 and 76 are moved outwardly of the line of pull of the toggle springs73 and 75, so that these toggle springs will then act to resilientlyurge the lever 64 in a direction toward the cam disc 49. The lever 64will theh exert a force on the annular clutch member 44, moving thismember against the force of spring 48 in a direction away from the outerend surface of the valve body extension 35 and releasing the frictionalengagement between the friction ring 47 and the opposed surface of thevalve body extension. With this friction released, the spring 43 willimmediately turn the shaft 42 and the valve plug 24 to the valve closingposition of the valve plug, thereby cutting ofi further flow of gasthrough the valve to the burner 18.

When the shaft 42 turns the valve plug 24 to its valve closing position,it also turns the cam disc 49, bringing the peripheral cam 84 of the camdisc against the arm 78 to release the dog 82 from the detent 72, andbringing a tapered cam 85 on the side of the cam disc 49 adjacent thelever 64 into engagement with theouter end of the detent 72, returningthe lever 64 to its original position in which the toggle springs 73 and75 assist the compression spring 48 in applying pressure to the frictionring 47. The cut off mechanism is now reset, and when the valve 12 isagain manually opened, this valve will be maintained in. variousselected positions of rotational adjustment to which it is manuallymoved and will be automatically reclosed if the burner flame is againextinguished.

In the modified arrangement illustrated in Figures 6 and 7 there are nopilot tubes 33 and each burner is provided with its individual pilotincluding a pilot flame nozzle 88 disposed adjacent the upper surface ofthe burner ring and connected directly to the main gas conduit 10 by atubular conduit 89. In this case the heat responsive element, instead ofa tubular coil 52 as in the first described form of the device,comprises a tubular ring 90 extending around the top surface of theburner ring 19 adjacent the flame apertures 20 and connected to theouter end of the bore 54 in the plug 55 by a tubular conduit 91.Otherwise the modified form of the invention is the same as thatillustrated in Figures 1 to 5 inclusive and described above.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are, therefore, to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are, therefore, intended to be embracedtherein.

What is claimed is:

1. A safety valve for gas burners comprising: a valve body; a valve plugmounted in the body for rotatable movement between open and closedpositions; a shaft connected to the plug for rotation therewith to saidpositions; spring means associated with the shaft and plug tensioned tonormally rotate the shaft and plug to the closed position; meansconnected to the shaft against rotation relative thereto and springbiased longitudinally of the shaft into engagement with the body to holdthe shaft and plug against rotation under the force of the spring meansto said closed position; heat-responsive means mounted on said body andadapted to deflect to a first position when heated and to a secondposition when cooled; a pair of complementary latch elements oneassociated with the shaft holding means and the other with theheat-responsive means, said latch elements deflecting with theheat-responsive means on cooling of said heat-responsive means andresultant deflection thereof from the first to the second positionsthereof, whereby to free the shaft and plug for rotation to said closedposition under pressure of the spring means; and cam means rotatablewith the shaft and arranged to disconnect the elements on rotation ofthe shaft and plug to said closed position, thus to free the shaftholding means for return movement into engagement with the valve body.

2. A safety valve for gas burners comprising: a valve body; a valve plugmounted in the body for rotatable movement between open and closedpositions; a shaft connected to the plug for rotation therewith to saidpositions; spring means associated with the shaft and plug tensioned tonormally rotate the shaft and plug to the closed position; meansconnected to the shaft against rotation relative thereto and springbiased longitudinally of the shaft into engagement with the body to holdthe shaft and plug against rotation under the force of the spring meansto said closed position; heat-responsive means mounted on the body andadapted to deflect to a first position when heated and to a secondposition when cool-ed; a pair of complementary latch elements oneassociated with the shaft holding means and the other with theheat-responsive means, said latch elements deflecting with theheat-responsive means on cooling of said heatresponsive means andresultant deflection thereof from the first to the second positionsthereof, whereby to free the shaft and plug for rotation to said closedposition under pressure of the spring means; and cam means rotatablewith the shaft and arranged to disconnect the elements on rotation ofthe shaft and plug to said closed position, thus to free the shaftholding means for return movement into engagement with the valve body,said heat-responsive means deflecting between said first and secondpositions thereof in a direction paralleling the axis of rotation of theshaft and the path of movement of the shaft holding means longitudinallyof the shaft, to bodily shift the latch elements in said direction whenthe elements are moving the shaft-holding means out of engagement withthe valve body, said cam means extending across said path when rotatedby the shaft to bias one of the latch elements laterally out ofengagement with the other when the elements are to be disconnected.

3. A safety valve for gas burners comprising: a valve body; a valve plugmounted in the body for rotatable movement between open and closedpositions; a shaft connected to the plug for rotation therewith to saidpositions; spring means associated with the shaft and plug tensioned tonormally rotate the shaft and plug to the closed position; meansconnected to the shaft against rotation relative thereto and springbiased longitudinally of the shaft into engagement with the body to holdthe shaft and plug against rotation under the force of the spring meansto said closed position; heat-responsive means mounted on the body andadapted to deflect to a first position when heated and to a secondposition when cooled; a pair of complementary latch elements oneassociated with the shaft holding means and the other with theheat-responsive means, said latch elements deflecting with theheat-responsive means on cooling of said heatresponsive means andresultant deflection thereof from the first to the second positionsthereof, whereby to free the shaft and plug for rotation to said closedposition under pressure of the spring means; and cam means rotatablewith the shaft and arranged to disconnect the elements on rotation ofthe shaft and plug to said closed position, thus to free the shaftholding means for return movement into engagement with the Valve body,said heat-responsive means deflecting between said first and secondpositions thereof in a direction paralleling the axis of rotation of theshaft and the path of movement of the shaft holding means longitudinallyof the shaft, to bodily shift the latch elements in said direction whenthe elements are moving the shaft-holding means out of engagement withthe valve body, said cam means extending across said path when rotatedby the shaft to bias one of the latch elements laterally out ofengagement with the other when the elements are to be disconnected, saidone latch element being pivotally connected to the heatresponsive meansfor swinging movement transversely of the direction of deflection of theheat-responsive means, to effect the lateral biasing of said one latchelement.

References Cited in the file of this patent UNITED STATES PATENTS672,990 Shoemaker Apr. 30, 1901 804,509 Ury Nov. 14, 1905 1,295,495 HeinFeb. 25, 1919 1,779,118 Deters Oct. 21, 1930 1,930,007 Franzen Oct. 10,1933 2,567,123 Ray Sept. 4, 1951

